The gameplay doesn't differ much from RA2 at this point, I'd like to shift it further but apparently so far everything I did just shifted more towards the mass-everything-to-win aspect. There might be even less options to micro at the moment. Keep in mind that everything seen are WIP.

Why OpenRA... well, YR is limited. There are a LOT of YR limits which are messy - if you look at Mental Omega, it pretty much showcases everything that engine can do, including bugs and whatnot. In order to grow YR, you need C++ and assembly knowledge and even then, you'll grind teeth to get something working (I participated in Ares development for a while so first-hand story). In order to grow OpenRA, you need only C# knowledge (YMMV if it's easier than C++ or not) and a lot less teeth grinding due to OpenRA being opensourced, with quite well-readable selfexplaining code. OpenRA devs also shifting focus to promote OpenRA as an engine and actively encouraging mods to create their own customized OpenRA as their project's platform. I can code in C# as well and I definitely find easier to code features into OpenRA than coding the same features to YR/Ares.

What this allows from a modder POV: Generals logics (everything excluding mob logic is already possible/simpler to implement than say, YR mindcontrol from what I know), area-of-effect damage promoting the unit (in order to create AoE damage in YR/Ares, one would rely on animation damages, which doesn't give experience - OpenRA lacks this option, but a projectile in OpenRA can have unlimited amount of warheads with delay option instead, which means a lot of c'n'p instead as AoE but also handling experience), a LOT better aircraft handling (which basically feels like Generals's except without guard mode - in RA2 aircraft couldn't even use waypoints or any way to queue orders, required constant attention), and a lot of hardcoded limits being exposed (more than 2 veterancy levels, lot more refined death animations and mutation handling - see Mental Omega's Clairvoyant/Duplicant, where the drone is required to have the human death animations (flameguy, radiation, etc.) in order to be upgradable via the support power -, mixable infantry/vehicle properties (YR has infantry hardcoded to share their cells for example, OpenRA has no actual distinction between infantry and vehicles internally) and the list goes on.